Compressor unit of a pulsator system



Feb. 12, 1935. I B, VON QBERSTADT 1,990,680

COMPRESSOR UNIT A PULSATOR SYSTEM Filed Feb. 27, 192 2 Sheets-Sheet 1 .la f f d5 l' s 3 2z 3 .si 1

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' colPREssoR UNIT or' A PuLsATonv ss'rsl Filed Feb. 2'7, 1932 2 Sheets-Sheet 2 2 ATTORNEYS Patented Feb. 12, 193s UNITED STATES 1,990.6 come-ssen oNrr or a rULsa'ron srs'rnm `Bnpp von Oberstadt, Berlin-Halensee, Germany,

asignar ot one-hall' to Franz Hebhold, Berlin- Halensee, Germany Application February 27, 1932,-Serlal No.,595,482 In Germany February 28, 1931 12Claims.

My invention relates to a hydraulic brake apparatus destined for automobiles and comprising staged pistons, the piston having the smaller diameter being connected to the operating rod sys- 5 tem 'and a yielding piston closing the annular space between the two'piston stages. Both pistons travel conjointly along a course corresponding to the replenishing volume, whereupon thepiston having the large diameter comes to rest and only the piston having the small diameter executes the course corresponding to the pressing volume. vThe improvement consists in a latch mechanism connecting both pistons only during their common replenishing course and being provided with an adjustable separatingmeans, by which the connection between the two pistons is loosened shortly before the of the pressing course, so that during the pressing coursel the moving smaller piston is separated from the stationary larger piston. A

The adjustation of the moment of said separation allows to compensate from a single central place the play generated at all the braking places, that is to say at all the four wheels by the wear of the braking members. Following the wear of the braking members such compensation elfects a pressing volume consonant with the original condition -of the brake system before the wear and tear.y

Prior braking systems are based on the principle that the quantity of the'iluid filling the network of the conducting mains is enlarged. Such an enlargement is made unnecessary by the present purely mechanical adiustation appuatus, at least in the case that the original quantity of the fluid illling the conducting mains is preserved, that is to say that no losses have taken place. With other words: the plays generated by mechanical wear, and eventually small fluid losses too, are compensated by the present` me-; chanical adjustation apparatus.

Dining the replenishing course the motion of the operating rod istransierred onto the annular piston having the large diameter by means of l5 the latch mechanism. The sectional area of the inner piston having the small diameter is several timesas great as the sectional area. of the opefrat-` ing rod, with the result, that the pressure reacting onto the operating rod from said small piston may iv be larger and therefor the course described by the operating rod during the replenishment may be smaller than desired. Accordingly it is preferred to interpose a lever system becoming eil'ective during the pressing course between the operating' i6 rod and the-.small piston.

(cl. sci-54.6)

The said lever system is arranged at right l angles to the latch mechanism for the purpose to mount both onthe same portion of the length of the brake applying system.

An embodiment of my invention is illustrated in the annexed drawings in which Figure 1 is a longitudinal sectional view showing the whole Aarrangement including the latch mechanism;

Figure 2 is a fragmental longitudinal sectional view taken at right angles to the sectional view shown in Figure 1 and showing the lever system; and Y f Figure 3 is the front view of a detail.

Figure 4 is a longitudinal sectional view showing 'a section corresponding to Figure 1 on a larger scale and showing the parts in a position brake Vshoes are brought to the wheels. Fig. 5 is a longitudinal sectional view similar to Fig. 2, the parts, however, lbeing in operated position.

Referring now to the drawings, the master or compression cylinder a is provided with an outlet member al, with which `a member a* for attach'- ing the main pipe leading to the braking cylinders is The annular piston b havcorresponding to that moment in which the ing a large diameter reciprocates within the master cylinder' a.V A cylindrical recess of the annular piston receives a portion -of the interior piston c. A collar d consisting of yieldable material is arranged between the cylinder a and interior piston c and provided with outer and inner anges d; and de tightening on the cylinder a and interior'piston c. A weak spring f being supported by the cylinder end wallc3 acts upon an annular sheet metal washer e y laid vinto the collar d and tends to push the annular piston b in its extreme backward position. Said position is deiined by a perforated wall g abutting against the outer and inner flanges ia and ib of a collar arranged at the inside of the cylinder cover k. The annular piston l has a long backward extending hub b1 provided with a shoulder b2 abutting against the wall g in the extreme backward position of the piston b.

A second weak spring h is interposed between the outlet member .a1 and the interlorpiston e provided at its front side with an annular groove c1. The hole into which the member a1 is threaded, has a diameter suillciently great that, after threading out the member a1, the spring h and piston e may be removed at the front side andinsertedagaininthesamewam .'I'heinnerportionb1i oftheannularpiston b whereas a Projecting edge o Islivpillilllleofthelateh.

is provided with a hole or perforation b4 for the purpose that the motion of the interior piston c relatively to the annular piston b is not prevented by air pressure.

Acylindricalhousingm isscrewedupon the backward portion of the cylinder a and may be adjusted and secured in its longitudinal position by screwing backwardv or forward.

'Ihe housing 1n is provided at its backward end with a stepped portion m1 and a narrower cylindrical projection m3' extending backward. A bushing n abuts against the stepped portion m1 and is provided with a cylindrical inner wall against which bears an annular operating member o. Said member is ilxed upon an operating rod p having a thickened end portion p1 extendingintotheborecofthelonghubcoftheinteriorpistonc. I Itistobeseenthattheoperatingrodpisledontwoplaces,thatistosay, within the hub c, of the interior piston c by means of the thickened portion p1 and within tble bushing n by means of the operating mem- The thickened portion p1 is provided with a longitudinal groove p for the purpose that `no air cushion is formed before the thickened portion p1 of the rod p.

The hub bl of the annular piston b carries upon its backward end a plate q pressed or otherwise xed upon said hub and provided with two diametrically opposed pairs of ears q1. A driving latch member sis linked by means of a pivot r between the ears of each pair and provided with two sloping faces s1 and s* joining together to form a roof shape. The latch member sis always pulled inwardly by a spring t and abuts withits interior sloping face s1 against a correspondingly sloping face ol of the operating member o, of said member prevents the latch member strom being swung inwardly above a desired limit.

During the first portion of the forward course of the operating rod p (the forward direction being from righthand to'lefthand side in Figures 1 and 2) the latch member s abuts with an outer longitudinal face 8 against the cylindrical inner facenlofthebushingn (Fig. l). Inthisposition the operating rod p' together with the operating member o, the two opposed latch membeni s, the plate q, the hub bl'of the annular piston b and said piston itself, and the interior pistonedrivenhvytheportionb3 oftheannular pistonv b. are driven together in the forward directio so thatl both pistons move conjointly and describe a large volume, thereby `overcoming the small resistance Vexisting during the replenishing course. Y

As soonas the edge x4, beingthe backward end ofthelatchmember face shas reached the frontedge n of Athe bushing n, the faces o1, s1, cooperatinginthemannerofslopingplanurge the latch members s outward. thereby overcomingtheoftheweakspringst. The member face sz is the sameasthe sloping angle of thefron'tyface n3 of the bushing n. .In consequence thereof, the latch member s does not participate furthermore on the motion of the operating member o, but escapes into the portion of the housing m, withthe result, that all the parts being connected with the latch member s, .especially the annular piston b, come to rest under the influence of the spring l, whereby the end position reached by the annular piston b is defined by the longitudinal position of the bushing'facenland therefor may A piston be adjusted by screwing the housing m along the cylinder a. But inasmuch as the driving member o is concerned, it moves unimpededly further, its cylindrical outer face on sliding .iongitudinally along the inner edge faces a5 of the latch members s, so that the latch members s remain' disconnected for the duration of the pressing course.

A plate u is fixed upon the backward end of the' hub cl ofthe interior' piston c and abuts against a shoulder b5 formed on said hub c. This plate u is formed with two diametrically Opposed arms u1 Fig. 2, each being provided with a projection u extending backward. The arms u1 are arranged in a plane at right angles relative to the plane of the latch members s, as best shown in Figures 1 and.2. At either side of the plate u, the plate q is prolonged .to form backward extending arms q, upon each of which a bell crank lever w is mounted by means of a pivot v. Either lever is formed with a nose w1 abutting against one of the projections u. The backward end of each lever carries a roller .1: cooperating with a cam or key-shaped second operating member y fixed upon the operating rod p, abutting against a shoulder p3 formed on the rod p and forming an abutment for the first operating member o, which is formed with two diametrically opposed recesses o, allowing the separation of the bell crank levers w, as best shown in Figures`2 and 3.

It is very important that the two lever arm lengths Ll and L2 (Fig. 2) of each bell crank lever w are unequal, so that a ratio diilering from one to one exists between the exerted forces.

As long as the motion is transmitted through the latch members s in the manner specified above, the rollers x occupy their most inward positions shown in mure 2, that is to say, the positions before the scondoperating member 1l. As soon as the latch members s are swung out and thepivot v of each bell crank lever w is come to rest together with the annular piston b, whereas the operating rod p moves further, the second driving member y slides along under the rollers s and its cam or key- 'ped faces pull outward the rollers x, s'o that the plate u is engaged at its projections uz by the lever noses w1 and driven forward. This motion is transmitted through the hub c to the linterior piston c, so that the interior only describes the pressing course. but with a smaller velocity than the operating rod p. The ratio of the velocities depends upon the ratio of the lever arms Llto L. and furthermore upon the cam face of the second operating member y. inasmuch this cam face may bechosen conveniently, the ratio of the velocities may be adapted to the increasing pressure of the brake members.

If the driver finds, that owing to wear in the lining or leather of the brake bands or shoes, an effective brakingcannot be accomplished. the operating rod p being in its end position, he has only to adjust the housing m by screwing it 'over the cylinder a to a length corresponding to amount of wear. The hydraulic brake mechanism will then operate again withthe initial correct efiiciency.

All the parts are returned by motions in the reverse direction and reversesequence. Thereby it is important that the spring h effects a positive engagement between the rollers :c and the second driving member y and that the springs t swing inward the latch members s, as soon as the operating member o '.1 we; with its edge o1 thelatchmemberodgeloinitsreturnmotion.

moves thereby 1. In a hydraulic control u nit,A the combination of a cylinder, a housing on said cylinder, an annular piston provided with an elongated hub in said cylinder, an interior piston provided with an elongated hub in said annular piston, said hub of both pistons extending intosaid housing, a rod extending through said housing and also extending at its inner end into the hub of said interior piston, latch meansconnected within the housingto said hub of the annular piston, lever actuated means connected to the hub of said interior piston within said housing, means carried by said rod for rst operating upon said latch means for synchronously moving. said pistons inwardly within said cylinder, and means on said rod .for operating said lever means for further moving said interior piston within said cylinder after movement of said annular piston has terminated. e

2. In a hydraulic control unit, the combination of a cylinder, a housing on said cylinder, an annular piston provided with an elongated hub in said cylinder-an interior piston provided with' an elongated hub in said annular piston, said hubs of both pistons extending into said housing, a plate provided with ears fastened to the outer end of said hub of the annular piston, said plate also provided with outwardly extending arms, bell crank levers pivotally mounted on said arms, spring pressed latch members pivotally mounted onl said ears, a rod extending at its inner end into the hub of said interior piston, a plate provided with arms fastened to the outer end of the hub of the interior piston, said bell crank levers adapty spring pressed latch members pivotally mounted on said ears and adapted to be operated upon by said operating member for forcingv both pistons towards the inner end of said cylinder, and cam means fastened to said rod and adapted to operate upon said bell crank levers for causing said levers to press upon` thearms of said plate for further moving the interior piston within said cylinder after the annular piston is at rest, stantially as shown and described.

3. In a hydraulic control unit, the combination of a cylinder, a housing adjustably mounted on said cylinder, an apertured wall in said cylinder, a flanged packing in said cylinder disposed against said wall, acover in the outer end of said cylinder against said packing, an annular and an interior piston in said cylinder between said wall and the inner end of the c'ylinder,"means in said housing and connected to bothpistons for moving the same synchronously towards the inner end of said cylinder, and means in said housing and connected to said interior piston for imparting further movement thereto while the annular piston is stationary.

4. In a hydraulic control una, indemnisation.

of a cylinder, a housing adjustably mounted on said cylinder, a pair of pistons in said cylinder and provided with hubs extending into said housing, latch members provided with means connecting the same to one of the hubs within said housing, levermeans provided with'meaas operably connecting the same to the hubsoL/'he other piston within' said housing, operating means in said housing and iirst operating on said latch members for imparting synchronous movement to said pistona and operating means inV said housing for` imparting movement to said lever means for operating the hub and its piston carrying said lever means after movement of the latch members has ceased.

5. In a hydraulic control unit, the combination of a cylinder, a housing on said cylinder, an an, nular piston provided with an elongated hub in said cylinder, an interior piston provided with an elongated hub inV said 'annular piston, said hubs of both pistons extending into said husing,

a plate provided with ears fastened to the outer end of saidA hub of the annular piston, said plate also provided with outwardly extending arms,V

spring pressed latch members pivotally mounted onlthe outer endsof said ears, bell crank levers pivotally mounted on the outer ends of said arms, a plate provided with arms iixedly secured to the outer end of the hub of the interior piston, said plate positioned between said first mentioned arms, said bellcrank levers adapted to operate' member and adapted to operate' upon said bell crank levers for causing the same to bear against the arms of the plate carried by the hub of the interior piston, for forcing the interior piston further inward after movement of the annular piston has terminated, substantially as shown and described.

6. In a hydraulic control unit, the combination of a cylinder, a housing adjustably mounted on said cylinder, a pair of pistons, one within the other, positionedin said cylinder, said pistons provided with hubs extending into said housing, means in said housing and operating upon the hub of one of the pistons for moving the same inwardly, means in said housing and operating upon the hub of the other piston for giving this last mentioned piston a further movement within said cylinder, and means associated with said operating means for adjusting the stroke of movement of the operating 'means by adjusting the housing upon said cylinder.

7. In a hydraulic control unit, the combination of a cylinder, a housing provided with an open outer end mounted upon said cylinder, a bushing in the open endof said housing, said bushing provided with a bevelled latch member engaging face, a pair of pistons in said cylinder and provided With; nested hubs, said hubs extending into'said housing, latch members provided with means connecting the same to one of said hubs, said latch members adapted to engage said bevelled latch member engaging face on said bushing, a rod extending into the hub of one of said pistons, an operating member fastened .to said rod within said bushing, ,Said operating mem ber provided with a bevelled face engaged by said latch members during the stroke prior to the latch members being forced into engagement with said bevelled face of said bushing. and said rod provided with means connecting t'her movement to this last hub and its piston inthe same to one of said hubs for impartingiurdependent of the hub to which said latch members are connected.

8. In a lrvdraulic control unit, the combination oi' a cylinder, a housing adjustably mounted on said cylinder, a pair of nested pistons in said cylinder, latch means in said housing and connected to one of the pistons for moving both pistons synchronously together within said cylinder, and lever means in said housing and connected to the other piston for imparting further movement thereto. i

9. `In ahydraulic control unit, the combination of a cylinder, a pair of nested pistons operating in said cylinder, means for moving said pistons to displace the liquid in the head of the cylinder, a housing adjustably mounted on said cylinder, positive locking means mounted in said housing for locking one of said pistons against return movementwhen under pressure of the liquid in the head and during the continued movement forward by the other piston.

10. Ina hydraulic control unit, the combination of a cylinder, a pair of nested pistons operating in said cylinder, means for moving said pistons to displace the liquid in the head of the cylinder, latch means connected to one of the pistons for moving both pistons synchronously together within said cylinder, lever means connected to the other piston for imparting further movement of the latter, a housing adjustahly mounted on said cylinder, positive locking means mounted onsaid housing cooperating with said latch means for locking one of said pistons against return movement when under pressure of the liquid in the head and during the continued movement forward by the other piston.

11. In a hydraulic control unit, the combination of a cylinder, an annular and an 'interior piston operating in said cylinder, means for operating upon said annular piston for synchronously moving both pistons, means for operating only upon said interior piston to displace the liquid in the head, a housing adjustably mounte 'l on said cylinder, positive locking means mounted in said housing for locking said annular piston against return movement when under pressure of the liquid in the head and during the continued movement forward by the'intervior piston.

12. In a hydraulic control unit, the combination of a cylinder, an annular piston provided with an elongated hub in said cylinder, an interior piston provided with an elongated hub in said annular piston, said interior piston extending a distance into the hub of said annular piston and with its hub projecting a distance beyond the outer end of the hub of said annular piston, means for moving said pistons to displace the liquid in the head of the cylinder, a housing adjustably mounted on said cylinder, said both hubs extending into said housing, means in said housing operating on the hub of said annular piston for synchronously moving said pistons inwardly within said cylinder, means in said housing operating on the hub of saidy interi or piston for further advancing the latter, positive locking means mounted in said housing for locking the annular piston against returnv move- 4ment when under pressure of the liquid in the head and during the continued movement forward by the interior piston.

' BOPP von OBERSTADT. 

